Within the field of display apparatus, liquid crystal display apparatus can have characteristics of thin profile and low power consumption. A liquid crystal display apparatus provided with a TFT (active-matrix) substrate having a switching element such as TFT at each pixel, especially has a high contrast ratio and excellent response characteristics and exhibits high performance. Therefore, it is suitably used for, for example, a television receiver, a personal computer.
A television receiver (hereinafter, referred to as a TV receiver) provided with a liquid crystal display apparatus includes, for example, a display panel having a surface to display an image in front of it, a display module having a backlight unit to irradiate a rear surface of the display panel with light, a front cabinet covering the periphery and side of a front surface of the display module, and a rear cabinet covering the rear surface of the display module.
The display panel includes a TFT substrate and an opposite substrate (a color filter substrate, a CF substrate) facing each other, a liquid crystal layer provided between the TFT substrate and the CF substrate as a display medium layer, a frame-shape sealing member for bonding the TFT substrate and the CF substrate together and sealing the liquid crystal layer into a space between the TFT substrate and the CF substrate.
A plurality of gate wirings (scanning wirings) and a plurality of source wirings (signal wirings) each crossing the respective gate wirings are provided on an insulation substrate of the TFT substrate. An area surrounded by two neighboring gate wirings and two neighboring signal wirings constitutes a pixel area, and, a TFT, and a pixel electrode made of, for example, ITO (Indium-Tin-Oxide) film are arranged in each of the corresponding pixel areas. The pixel electrode is covered by an alignment film.
The alignment film is made of a material such as polyimide and formed so as to cover a display region which includes the plurality of pixel areas, for example, using an inkjet method. Since the material for the alignment film, such as polyimide, has a low viscosity, the resulting alignment film often wettingly spreads to the edge of the substrate from the display region when the material is applied to the display region using inkjet method. If the alignment film spreads to a sealing member forming region, it may cause deterioration of adhesion between the sealing member and the substrate, resulting the peeling of the sealing member.
JP 2007-322494 A (hereinafter, referred to as Patent Document 1) discloses an invention of a liquid crystal display apparatus configured to include an insulation film, to which a step part is provided, between a display region and a sealing member forming region on a TFT substrate, such that grooves and protrusions are provided on a conductive film when the conductive film covers the step part.
FIG. 12 is a schematic plan view of a groove and protrusion part 27 of a display panel of the liquid crystal display apparatus of Patent Document 1, and FIG. 13 is a cross-sectional view along the line XIII-XIII of FIG. 12. A portion of the groove and protrusion part 27, which is corresponds to a part of the upper side of the display panel is shown in FIG. 12 and FIG. 13. The upper side of FIG. 12 corresponds to the sealing member forming region S on which the sealing member 4, described in the following paragraphs, will be formed, and the lower side corresponds to a display region D. A cover metal 25 and a conductive film 26 are omitted in FIG. 12.
As mentioned above, the TFT substrate 2 and the CF substrate 3 are bonded by a frame-shape sealing member 4 that is provided on the periphery of the CF substrate 3. The groove and protrusion part 27 is provided between the display region D and the sealing member forming region S.
As shown in FIG. 12, the signal wirings 22 on the TFT substrate 2 are disposed to extend at a predetermined angle to the row direction at the inner side of the sealing member forming region S (the area closer to the display region D). The signal wiring 22 are disposed to cross across the groove and protrusion part 27, extend at a predetermined angle to the row direction at the outer side of the display region D (the area closer to the sealing member forming region S), and then extend in the column direction in the display region D (not shown).
A second interlayer insulation film 24 in the groove and protrusion part 27 includes three grooves 249 each extending in the row direction and positioned side by side in the column direction.
As shown in FIG. 12 and FIG. 13, the signal wirings 22 are formed on, for example, the insulation substrate 21 such as a glass substrate of the TFT substrate 2, and a first interlayer insulation film 23 is formed on the signal wirings 22.
A cover metal 25 is formed at a portion corresponding to the groove and protrusion part 27 on the first interlayer insulation film 23 and above the signal wirings 22.
The second interlayer insulation film 24 which is formed by an organic insulation film such as photosensitive acrylic resin is provided in such a way to cover the first interlayer insulation film 23 and the cover metal 25, and a groove 249 is formed by patterning.
Further, a conductive film 26 made of ITO (Indium-Tin-Oxide) is formed by vapor deposition in such a way to cover the second interlayer insulation film 24. On the conductive film 26, a groove 269 is formed at a position corresponding to the groove 249.
In this liquid crystal display apparatus, a wet-spreading of the polyimide can be blocked by the level difference in the groove and protrusion part 27 when an alignment film 6 made of polyimide is formed on the conductive film 26 at a position corresponding to the display region D, and further, it is expected that the wet-spreading of the alignment film 6 will be further prevented due to a low wettability of polyimide to ITO.